High temperature high pressure apparatus



United States Patent HIGH TEMPERATURE HIGH PRESSURE APPARATUS 9 Claims, 6 Drawing Figs.

US. Cl. 219/50. l8/16.5. 34: 219/149, 152 Int. Cl 1105b 1/00, B290 l/00 Field of Search 219/50.

149.150, 151, 152; 18/34, 38, 16.5, (High Pressure Digest); 219/50 References Cited UNITED STATES PATENTS 3,134,739 5/1964 Cannon 252/503X 9/1964 Wentorf, Jr., et al. 252/503 2,941,252 6/1960 Bovenkerk 18/34(M) 3,030,661 4/1962 Strong l8/34(M) 3,350,743 11/1967 lshizuka... l8/(High Pressure Digest) 3,407,445 10/1967 Strong ]8/34(M) Primary Examiner.l. V. Truhe Assistant Examiner-Hugh D. Jaeger Attorney-Mason, Fenwick & Lawrence ABSTRACT: High-temperature high-pressure apparatus comprising pair of opposed tapered pistons having truncated flat end surface, annular die member having straight cylindrical inner wall, said wall defining aperture into which said pistons converge, rigid hollow cylindrical body made of material having relatively low compressibility coefiicient said body being coaxially placed in said aperture, reaction chamber formed by piston ends and inner wall of the body, gaskets placed upon the ends of said cylindrical body and sealing gaps between said pistons and die inner cylindrical wall, and means for electrically heating reactant in said reaction chamber, the temperature and pressure caused in the reaction chamber being damped by said cylindrical body, thereby lowering the pressure and temperature transmitted to said die member, said gaskets pressing the ends surface of the body whereby the body walls are prevented from rupturing at pressure higher than that induced by the material of the body itself characterized in that the opposite ends of the rigid hollow cylindrical body is formed with tapered surface.

n V I PATENTEDnEc emu 3 546413 sum 2 or 2 HIGH TEMPERATURE HIGH PRESSURE APPARATUS The present invention relates to improvements in or relating to high-temperature high-pressure apparatus, more particularly a high-temperature high-pressure apparatus which has a rigid hollow cylindrical body and is used for the synthetic production of diamonds and for various high-temperature high-pressure experiments.

Previously, I proposed ahigh-temperature high-pressure apparatus having a pair of opposed tapered pistons or punches each having a truncated flat end surface, an annular die member having a substantially cylindrical wall of a diameter larger than that of each piston truncated end surface, a hollow cylindrical body made of low compressibility coefficient material and having an inner diameter substantially the same or slightly smaller than the diameter of said flat end surface of each piston and positioned coaxially within the die cylindrical wall, and gaskets placed respectively at the ends of said cylindrical body, a reactant being compressed and heated within a reaction chamber within the hollow body, the pressure and temperature directed to the reactant being higher than that of the die by the interposed damping effect of the hollow body thereby preserving the die.

The features of the previous apparatus are a high-temperature high-pressure apparatus comprising a pair of opposed tapered pistons respectively having a truncated flat end surface, an annular die member having a straight cylindrical inner wall, said wall defining an aperture into which said pistons converge, a rigid hollow cylindrical body made of material having a relatively low compressibility coefficient, said body being coaxially placed in said aperture, a reaction chamber formed by the piston ends and the inner wall of the body, gaskets placed respectively upon the ends of said cylindrical body and sealing the gaps between said pistons and die inner cylindrical wall, and means for electrically heating a reactant in said reaction chamber, the temperature and pressure caused in the reaction chamber being damped by said cylindrical body, thereby lowering the pressure and temperature transmitted to said die member, said gaskets pressing the end surfaces of the body whereby the body walls are presented from rupturing at a pressure higher than that induced by the material of the body per se.

The inner shoulder of opposite ends of said hollow cylindrical body in the previous apparatus is a right angle. When the pistons converge into the aperture which is defined by the wall of the annular die member, the inner shoulder of the hollow cylindrical body is often broken and there is a tendency for the shoulder of the truncated flat ends of the pistons to be broken.

As a result, there are disadvantages in that the movement of the pistons also, unsmooth and the pressure generated becomes'unstable and the pressure gradient along the side surface of the punch is not uniform. These disadvantages cannot be overcome by using a gasket only.

The present invention is to overcome the above disadvantages by modifying theforrn and construction of the rigid hollow cylindrical body. I

According to the present invention, therefore, I provide a high-temperature high-pressure apparatus comprising a pair of opposed tapered pistonsre'spectively having a truncated flat end surface, and annular die member having a straight cylindrical inner wall, said wall defining an aperture into which said pistons converge, a rigid hollow cylindrical body made of material having a relatively low compressibility coefficient, said body being coaxially placed in said aperture, a reaction chamber formed by the piston ends and the inner wall of the body, gaskets placed respectively upon the ends of said cylindrical body and sealing the gaps between said pistons and die inner cylindrical wall, andmeans for electrically heating a reactant in said reaction chamber, the temperature and pressure caused in the reaction chamber being clamped by said cylindrical body, thereby lowering the pressure and temperature transmitted to said die member, said gaskets pressing the end surfaces of the body whereby the body walls are prevented from rupturing at a pressure higher than that induced by the material of the body per se, characterized in that the opposite ends of the rigid hollow cylindrical body is formed with a tapered surface.

The present invention will be better understood from the following explanation of the preferred embodiments taken in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic view in section of the essential portion of the apparatus according to the present invention;

FIG. 2 shows another structure and position of the rigid hollow cylindrical body to be used for said apparatus;

FIG. 3 shows further structure and position of the rigid hollow cylindrical body to be used for said apparatus;

FIG. 4 shows yet another construction of the rigid hollow cylindrical body to be used for said apparatus.

FIG. 5 shows an enlarged section of one structure and position of the reaction chamber to be used for the apparatus of the present invention;

FIG. 6 shows an enlarged section of another structure and position of the reaction chamber for said apparatus.

In FIG. 1, the piston may be a truncated conical configuration as illustrated by 11. This is for the purpose of strengthening the piston by adding mass at the outer portion thereof, for the purpose of preventing the shoulder of the die member from being broken, and for making the height or axial length of the cylindrical body larger. The angle of the tapered surface is preferably 45 to 20 and more preferably 40 to 25 relative to the axis of the piston vertical line with theview of strengthening the piston by means of a supporting means.

The material to be used for the piston is generally WC-C alloy, but alloy steel may be also used. When a relatively lower pressure is employed in the apparatus, alloy steel sufficiently hard in the inside thereof may be used.

The annular die member has an inner cylindrical wall and connecting surfaces respectively opposedly tapered at an angle to said wall for the purpose as referred to above with respect to the piston. The wall is preferably vertical but there may be provided further intermediate tapered curved surfaces respectively connecting each of said strengthening tapered surfaces with the vertical wall defining a cylindrical chamber to snugly contain the hollow cylindrical body so that the shoulder may be minimized. Alternatively, the inner wall may be smoothly curved. The ratio of the diameter to that of the truncated flat end surface of the piston should be less than 0.8 for the reasons to be referred to hereinafter. Said ratio is more preferably such that the square of the former to that of the latter is less than 0.5 in the case where the die member is to be made of WC-Co alloy. When it is of carbon steel or of alloy steel said ratio must be less than 0.4 and preferably is less than The height or axial length ofthe cylindrical wall of the annular die member is generallyless than the dimension of the inner diameter of the annular die member. If the length is made longer the pressure resistibility of the die member is lowered because of the decrease of the amount of pressure absorption or damping effect of the hollow cylindrical body.

The die member is preferably prestressed by a plurality of binding rings made of hardened steel so as to counteract the tensile stress which occurs in the die member. The tapered surfaces of the die member are provided in order to strengthen its use for so-called mass support by making the outward portion thick, and'to prevent the shoulder portion from being broken. The strengthening angle may be further decreased if the portion to be stressed is positioned further inwardly or if the force to be applied to the die member is lowered.

The hollow cylindrical body is located in the reaction chamber defined by the cylindrical wall of the die and serves to prevent the temperature and pressure in the reaction chamber from being directly applied to the cylindrical wall which may otherwise cause rupture of the die member. The opposite ends of the rigid hollow cylindrical body is formed with a tapered surface. The cylindrical body may be made of alumina, magnesia, zirconia, thoria, beryllia, titania or other oxides which are rigid and of relatively lower compressibility coefficient and which are preferably sintered sufficiently so that the apparent specific gravity thereof comes close to the true specific gravity. Other refractory products comprising some constituent in addition to said oxide also may be used for that purpose but in such case the pressure damping effect is lowered to some extent. It is due to the fact that the cylindrical body is supported by the gaskets at the opposed ends thereof, which seal the gaps between the piston and die member, that the rupture of said cylindrical body due to expansion in the vertical direction may be prevented. The cylindrical body may thus be used under severe temperature and pressure conditions which the body material per se could not normally withstand. The result, which corresponds to the so-called quasi-isotropic pressure realized in known high-pressure apparatus, is established in said cylindrical body.

The pressure resistibility of the cylindrical body is varied depending on the material used for constructing said body. The maximum pressure resistibility can be attained when alumina is used, while in the case where thoria, zirconia, magnesia or the like is used the pressure resistibility is not as high.

The inner diameter of the hollow cylindrical body may be that of the diameter of the truncated end surface of the piston or slightly smaller than the diameter of the piston free end, depending on the axial length of the reactant to be filled in said cylindrical body. The axial length or the height of the cylindrical.body should be somewhat smaller than that of the inner cylindrical wall of the die member since the gaskets must be placed at the opposite ends of said cylindrical body.

on each end of the cylindrical body and in the adjacent gap between a piston and the die member is placed a substantial annular gasket, which may be made of a refractory material comprising an agalmatolite stonelike material having a relatively higher porosity which is preferably sintered slightly. The refractory material is preferably wrapped or sandwiched with well-tempered copper or iron foil. Other similar stony refractory materials such as natural agalmatolite, stealite and the like, various fibers, as well as plastics such as polypropylene may be used for this purpose.

The gaskets serve to seal the pressure produced in the reaction chamber and insulate the die member from electric current flowing from one of the pistons to the other through the reactant contained in the cylindrical body in order to produce the high temperature necessary for the reaction. Thus the gasket used in the present invention is utterly different in configuration, location, and function from the usual gasket used in the known high-temperature high-pressure apparatuses.

In FIG. 1, reference numeral 11 designates a tapered piston made of an WC-Co alloy. The strengthening wall of said piston is tapered by an angle, 30. The piston is surrounded by a binding ring 12 made of hardened steel which serves to strengthen th'episton by prestressing. A plurality of such rings may be mounted by well known methods in order to avoid rupture of the piston due to high pressure and high temperature. A piston 11'- having a strengthening ring 12' is provided in confronting relation to piston 11.

A substantially annular die member 13 is oriented in such a way that the inner cylindrical wall thereof is coaxially position'ed between said two opposed pistons 11 and 11. As seen FIG. 1, the die member is defined in section by line segments y-x, x-x and x-y. The segment x-x constitutes the inner wall of the die member which is made flat and substantially vertical. The segments X-y and xy' constitute strengthening walls. In this embodiment the die member is made of WC-Co alloy. The die member 13 is also surrounded by a plurality of binding rings, one of which is illustrated at 14 in FIG. 1, and is made of hardened steel which serves to prestress the die member to prevent rupture thereof. A ring (not shown) made of mild steel is provided to overlie ring 14 to remove the danger from flying bits of metal should explosion of the apparatus or the die memberoccur.

Mark a designates a hollow cylindrical body having tapered surfaces s and s made of alumina sintered at a temperature above l,500 C. such that the apparent specific gravity comes close to the true one. The outer surface thereof is abraded so that it may be snugly inserted in the aperture of the die member. The opposite ends of the cylindrical body are also subjected to grinding so that the end surfaces thereof are smooth. This cylindrical body serves, as stated above, to dampen the high pressure and high temperature caused by the movement of the pistons toward one another so that the die member may not be subjected directly to such severe conditions. It can serve also to thermally and electrically insulate the die member since it is made of'the hereinbefore mentioned oxide of refractory product. Y

Although'the die member is insulated by means of said cylindrical body from high temperatures in the reaction chamber and from electrical current, it-is preferable to provide a further thermal and electrical insulator. In the embodiment as illustrated in FIG. 1, there is provided a cylindrical member 15 made of sintered agalmatolite which forms a reactant vessel together with two discs 18 and 18', respectively made of steel. Between the receptacle assembly, consisting of the cylindrical members 15 and discs 18 and 18' and the end surface of the pistons 11, and 11 a pair of discs 16 and 16' are inserted respectively. Each disc 16 and 16 is made of sintered agalmatolite or the like, around the periphery of which a ring 17 made of steel is provided which forms an electric current path together with the disc 18, 18, also made of steel. In the vessel a specimen or reactant 19 is contained.

Numerals 20 and 20 designate gaskets which are'made of agalmatolite system refractory material which has been slightly sintered at a temperature such that the porosity comes to 10 percent to 30 percent.

The apparatus is mounted in an hydraulic press so as to move the punches respectively into thedie aperture to produce high pressure between the truncated end thereof. Since this area is surrounded by the die member 13 and gaps between the die member and pistons or punches 11 and 11 are sealed with gaskets 20 and 20', the pressure in the reaction chamber containing reactant 19 may be raised up to about 50,000 atmosphere. As stated this high pressure will not be transmitted directly to the wall of the die member owing to the presence of the interposed cylindrical body a. From an electric source, not shown, electrical current is applied to the punch ll which flows through the ring 17, disc 18, the reactant 19 and through the corresponding members on the other side in reverse direction to the punch 11', or vice versa, so as to cause a temperature of 1,2001,600 C. The reactant,

which is prepared by admixing particles of nickel and chromi' In FIG. 2, the hollow cylindrical body may be constructed with a hollow cylindrical member a ring members b and b having a trapezoidal section and ring members 0 and 0 having a triangular section.

In FIG. 3, the hollow cylindrical body may be constructed with a hollow cylindrical member a and ring members 50 and 51 each having a triangular section.

In FIG. 4, the hollow cylindrical body may be constructed with pair of hollow cylindrical members 60 and 61, a pair of ring members 70 and 71 each having a trapezoidal section and ring members and 81 each having a triangular section.

The above hollow cylindrical member is made of material which is rigid and of relatively low compressibility coefficient, and the ring member having a trapezoidal section or a triangular section is made of material which is rigid and of relatively low compressibility coefiicient or of refractory materials or metals, which are of less compressibility coefficient than the above material. The refractory materials are for example magnesia, agalomatolite, porous alumina and the like, The metals are for example iron, aluminum alloy, copper and the like.

A modification of the electric current path in the reaction chamber is illustrated in FIGS. 5 and 6.

In FIG. 5, the reaction chamber is constructed by circular discs 21 and 21, rings 22 and 22, hollow discs 23 and 23', rings 24 and 24', discs 25 and 25', circular thick discs 26 and 26, rings 27 and 27 ring 28 and cylindrical tube 29. The circular discs 21 and 21', rings 22 and 22, hollow discs 23 and 23, rings 24 and 24 and discs 25 and 25' are made of an electric conducting materials such as iron, nickel and the like. The circular thick discs 26 and 26', rings 27 and 27, ring 28 and cylindrical tube 29 are made of for example agalomatolite, magnesia. porous alumina and the like. A reactant 30 is charged in the reaction chamber.

Electric current applied to the punch flows through disc 21, ring 22, hollow disc 23, ring 24, the reactant 30 and through the corresponding members on the other side in a reverse direction to the other punch, or vice versa.

In FIG. 6, the reaction chamber is constructed by ring 31, disc 32, disc 33, cylindrical ring 34, hollow disc 35, cylindrical ring 36, disc 37, disc 38, cylindrical 31, 39, hollow disc 40, disc 41, cylindrical tube 42 and cylindrical tube 43. The ring 32, disc 32, disc 33, cylindrical ring 34, hollow disc 35, cylindrical ring 36 and disc 37 are made of an electric conducting materials such as iron, nickel and the like. The disc 38, cylindrical tube 39, hollow disc 40, disc 41, cylindrical tube 42 and cylindrical tube 43 are made of for example, agalomatolite magnesia, porous alumina and the like, A reactant 44 is charged in the reaction chamber.

Electric current applied to the punch flows through ring 3], disc 32, reactant 44, disc 33, cylindrical ring 34, hollow disc 35, cylindrical ring 36, to the other punch, or vice versa.

According to the improvements in the high-temperature high-pressure apparatus of the present invention, the following advantages can be attained.

l. Since the opposite ends of the rigid hollow cylindrical body are formed with tapered surfaces, the rupture of the inner shoulder of the rigid hollow cylindrical body does not occur.

2. The movement of the pistons is very smooth and so the pressure generated is very stable and the pressure generated is very uniform.

3. The life of pistons is very long, for example several thousands of operations.

4. The operation of the apparatus is very easy.

5. The working for the production of the apparatus is very simple.

6. A large-sized high-temperature high-pressure apparatus can be produced and also, as the material of the die member, alloy steel can be used.

7. Since the electric current path in the reaction chamber is improved as described hereinbefore, the current capacity can be decreased and heating due to the electric resistance is concentrated in the neighbourhood of the reaction chamber. Therefore, the temperature increase of punches can be inhibited and the life of punches can be increased.

. Since the indirect heating of the reactant can be effected, the temperature gradient in the reaction chamber is very uniform and thus a uniform reaction can be carried out to obtain a good product.

lclaim:

l. A high-temperature high-pressure apparatus comprising a pair of opposed tapered pistons respectively having a truncated flat end surface, an annular die member havinga straight cylindrical inner wall, said straight cylindrical inner wall defining an aperture into which said pistons converge, a rigid hollow cylindrical body coaxially placed in said aperture and having an outer wall engageable with said straight cylindrical inner wall of said annular die and an inner wall, a reaction chamber formed by the piston ends and the inner wall of the body, gaskets placed respectively upon the ends of said cylindrical body for sealing a space between said pistons and said straight cylindrical inner wall of said annular die member, and means for electrically heating a reactant in said reaction chamber, the tem erature and pressure caused in the reaction chamber being amped by said cylindrical body, thereby lowering the pressure and temperature transmitted to said die member, said gaskets pressing the end surface of the body whereby the body walls are prevented from rupturing at a pressure higher than that induced by the material of the body, characterized in that the opposite ends of the rigid hollow cylindrical body is formed with a tapered surface that is entirely within the confines of said straight cylindrical inner wall of said annular die member.

2. An apparatus according to claim 1, wherein the means for electrically heating a reactant in the reaction chamber includes means to effect a direct electric resistance heating and also effect an indirect electric resistance heating.

3. The invention of claim 2 wherein said means for electrically heating said reactant additionally includes an electrically nonconductive tube in which said reactant is positioned, a conductive disc extending over each end of said nonconductive tube, an electrically conductive means extending from said conductive disc inwardly along the exterior surface of said conductive tube for a distance less that the axial extent of said conductive tube having an end termination medially of said nonconductive tube, and hollow disc means engaging said end termination of said conductive means extending along the external surface of said tube, a hollow conductive ring engaging said hollow disc means and extending from said hollow disc means towards one of said tapered pistons and means providing electrical communication between said tapered pistons and said ring means contacting said hollow disc means for providing both direct and indirect heat to said reactant.

4. The invention of claim 2 wherein said means for electrically heating said reactant additionally includes electrical conductor means associated with each of said tapered pistons and contacting said reactant and nonconducting separator ring means separating the conductor means associated with the respective pistons whereby voltage applied across said pistons results in current flow which is substantially entirely directed through said reactant to provide for the direct heating thereof.

5. The invention of claim 4 additionally including electrical conductors in said electrical conductor means associated with each piston extending in enclosing relationship about a substantial portion of said reactant to provide for indirect heating of said reactant.

6. The invention of claim 2 wherein said rigid hollow cylindrical body is formed of sintered alumina sintered at a temperature in the range of 1 ,200- l ,600 C.

7. An apparatus according to claim 1, wherein the hollow cylindrical body is constructed with a hollow cylindrical member, pairs of ring members having a trapezoidal section and pairs of ring members having a triangular section.

8. An apparatus according to claim 1, wherein the hollow cylindrical body is constructed with a hollow cylindrical member and pairs of ring members having a triangular section.

9. An apparatus according to claim 1, wherein the hollow cylindrical body is constructed with pairs of cylindrical members, having a trapezoidal section and pair of ring members having a triangular section. 

